The authors present results for the "Impact Project Focus Area" on the topic of symbolic execution as used in software testing. Symbolic execution is a program analysis technique introduced in the 70s that has received renewed interest in recent years, due to algorithmic advances and increased availability of computational power and constraint solving technology. They review classical symbolic execution and some modern extensions such as generalized symbolic execution and dynamic test generation. They also give a preliminary assessment of the use in academia, research labs, and industry.